Method for casting metals



Feb. 15, 1938. J. A. scHULTz, JR.. ET AL 2,103,080

METHOD FOR CASTING METALS Filed March 19, 1954 4 Sheets-Sheet 1 Feb. 15193s.

J. A. SCHULTZ, JR., ET AL METHOD FOR CASTING METALS Filed March 19, 19344 Sheets-Sheet 2 Ja/m 1150/10/23 J/ Jahn 'A Zapf @du/5, Y I I abba/MMSFeb 15, 1938 J. A. scHULTz, JR., ET An. 2,103,080

METHOD FOR CASTING METALS Filed March 19, 1934 4 Sheets-Shes?I 5 wm-MJ22W K amas Fell 15, 1933 J. A. SCHUL-rz, JR.. ET AL 2,108,080

METHOD FOR CASTING METALS Filed March 19, 1934 4 Sheets-Sheet 4 ,Q s gmmm Q jl'e 59 l r l: I l |l RMN;

dumm@ Patented Feb. 15, 1938 UNITED STATES PATENT OFFICE METHOD FORCASTING METALS/ Application Maren 19,

Z Claims.

This invention relates to the art of making castings from molten metaland particularly to an improved method andv apparatus used for makingcastings under pressure. l

One of the objects ofthe invention is to provide a simple and eilicientmeans operated by suitable pressure whereby thin section castings can becheaply and rapidly made by persons un'- skilled in the art;

Another object of the invention resides in an improved method ofproducing castings by forcing the metal to be cast at a temperaturesubstantially that of its plastic state into a mold using acomparatively high pressure per unit of area and maintaining the moldarea in contact with the metal to cast at a substantially uniform lowtemperature.

Another object of the invention is `the provision of a method whichincreases the eiciency of the machine for larger scale production.

Another object of the invention is the provision of an improvedarrangement to-retain at all times in fixed cooperative relation withthe dies the metal forcing and delivering means so that changes intemperature or pressure due to displacement of the metal does not aiectsuch cooperative relation.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, operation and function of the relatedelements of the structure, to various details of construction and tocombinations of parts, elements per se, and to economies of manufactureand numerous other features as will be apparent from a consideration ofthe specification and drawings of a form of the invention.

Figure 1 is a side elevational View of the machine of the invention;

Figure `2 is a detailed sectional view taken substantially on the line2-2 of Figure 1;

Figure 3 is a View showing in detail certain parts of one of the safetyfeatures of the invention;

Figure 4 is a top plane view of the machine shown in Figure 1;

Figure 5 is a sectional view taken substantially on line 5 5 of Figure 1showing the cooperative relation existing between the die holding plateand the molten metal charging and delivering means;

Figure 6 is a sectional view taken substantially on the line B--G ofFigure 4;

Figure 7 is a detailed sectional view showing the die operatingmechanism;

Figure 8 is a detailed sectional view taken substantially on the line8-8 of Figure 7;

1934, Serial No. 716,248

Figure 9 is a detailed sectional view taken substantially on the line 99 of Figure 7;'

Figure 10 is aA detailed sectional view taken substantially on linesIII-l0 of Figure 7.

We have illustrated our invention as incorporated in a die castingmachine, but it is to be understood that we contemplate the use of ourinvention wherever the same may be found to be applicable. It is to beunderstood that we do not wish to limit the same to the disclosure shownin the drawings, but that the same 1s used for illustrating purposesonly.

The method of our invention in one of its aspects includes forcing intoa mold or die the metal to be cast at a temperature slightly higher thanits melting point or at a temperature where the metal could be termed asbeing at its plastic state, using, under suchA condition, for injectingthe metal into the die a pressure not less than one thousand pounds andnotgreater than two thousand pounds per square inch; the die castingmold being kept at substantially low temperature preferably at atemperature that does not exceed sixty percent of the temperature of theinjected metal.

As a practical illustration of the method of our` invention we havefound after considerable research and experimentation that with zincbase non-ferrous alloys having a melting 4point of 735 Fahrenheit byforcing the metal into the die or casting mold at a temperature rangingfrom 750 to 800 that is substantially at a temperature ranging from 3 to10 percent higher than that of the melting point, employing an injectingpressure of 1600 pounds per square inch; and retaining the mold area incontact with the cast metal at a temperature ranging from 375 to 400,that is a temperaturewhich is relatively lower than that of the injectedmetal, we have found that the most satisfactory results are obtainedwhen the temperature is not higher than percent of the injected metaltemperature. Careful tests show that the average tensile strength ofcastings produced by our method is increased by more than 10 percentover castings produced by any other method, the casting thus producedbeing non-porous and of remarkable high density and we are capable ofproducing castings of greater uniformity all held within closerdimensional limits than those produced heretofore. In addition byfollowing this method We have been able to successfully and cheaply makein large scale production castings of extremely thin wall sectionshaving as low as 0.013 inch in Wall thickness. Thus it can be seen thatby our method the main defects and disadvantages present in die castingsheretofore produced are obviated.

The process of the invention may be carried out by the utilization ofmachines of several types, and while we have disclosed the invention asbeing carried out in connection with a die casting machine using iiuidpressure, it is to be understood that we contemplate the utilization ofour process with-all kinds of machines whenever the 'saine is found tobe applicable, the machine disclosed herein being illustrated as one ofthe embodiments by which our method can be successfully carried inpractice.

Referring to the drawings and particularly to Figures 1, 4 and 6, thedie casting machine illustrated as one of the embodiments by which themethod of the invention can be carried out and other features of ourinvention comprises a frame IIJ having a base portion II forming theouter metallic casing of furnace I2 which is provided with a lining offire brick |4 forming a rire or furnace chamber I5. The furnace chamberI5 is closed at its upper end by a metallic plate I9 serving to supporta metal reservoir or melting pot 20 which extends downwardly from theplate Within the furnace chamber l5, the melting pot 20 being heated bysuitably regulated means conveyed through the furnace walls b) means ofa pipe 2| inorder to maintain the metal in the reservoir in a moltencondition at the desired temperature. Located within the melting pot 20is the supplemental pot or pressure delivery chamber 24 preferably of agooseneck configuration which is substantially immersed in the moltenmetal and is removably secured in xed relation to the melting pot 20 bymeans of clamps 23 secured to plate i9. Member 24 is provided with alateral connecting opening 2E whereby the molten material passes to acylindrical bore or duct 25 connected by means of passage 21 to thedelivering orifice or spout 2B. In order to force the molten metal intothe dies, the cylindrical bore 25 of member 24 is adapted to snuglyreceive a member or piston which is adapted to be moved by means of rod3| secured to a reciprocating piston 32 located within the cylinder 33.Cylinder 33 is fixedly supported upon plate i9 by means of a pluralityof upright supports 34.

Adjacent to the furnace i2 in proper spaced relation is a relativelystationary die holding plate 35 which is suitably supported andremovably secured to supplemental pot or pressure chamber E4 by means ofhinged members or eye bolts 36 having a threaded end portion adapted toreceive nuts BlmPressure chamber 24 is provided with projecting portionshaving suitable grooves 38 as shown in detail in Figure 5, which serveto receive bolts 36 and cooperating nuts 31 for the purpose of urgingthe molten delivering means of member 2t in proper positive engagementwith the die holding plate 35. The die holding plate 35 is provided withextending leg portions 3S, each carrying a wheel 4I engaging horizontalsupports 40 secured at one end to the walls of the furnace I2 bysuitable brackets and at the other end by suitable supporting members orbase support 42. This arrangement and type of support for the dieholding plate 35 permits the proper adjustability of the same withrespect to pressure chamber 24 and also permits that the die holdingplate be removed for repairs or change of dies, by the simple expedientof untightening or loosing nuts 31, permitting bolts 36 to be removedfrom grooves 38.

In the form of the embodiment illustrated in the drawings, the dies ormolds preferably used are of the sectional type consisting of at leasttwo relatively movable members, means are provided for supporting one ofthe die members relatively stationary and moving the other relativethereto. The latter means comprises a supporting and guiding frame 43formed of a' plurality of rods secured at one end to the relativelystationary die holding plate 35 and at its other end by a subframe 55. Amovable die holding plate 45 as particularly illustrated in Figures 1,4, 5 and 6 is provided with bosses or integral projections 46 havingopenings through which passes the members 43 thus supporting the dieholding plate 45 in proper alignment and guiding it in its relativemotion with respect to die holding plate 35.

The die holding plate 45 is connected to an adjustable movable link 41formed into two cooperating threaded portions, one of said portionsterminating into a spherical end 48 which is received in a centrallylocated boss formed integral with die holding plate 45 forming a balljoint connection permitting the proper motion of member 41. Theadjustable connecting link 41 is removably secured to plate 45 by meansof a removable bracket 49 having at one end an opening of similarcontour to the spherical end of member 41 and having at its other end afrustreconical opening in" order to permit oscillatory motion of member41. Member 41 serves as a pressure equalizing device for the properactuation and cooperative engagement of the relatively stationary diemember carried by die holding plate 35 and the cooperating die elementcarried by the movable die holding plate 45. Pressure equalizing member41 is pivotally carried at its other end by a stub shaft 50eceentrically carried by and between two oscillating members or gearsegments 54 journalled by suitable shafts on sub-frame 55 which is alsoprovided with suitable openings to receive guiding members 43. Frame 55is adjustably supported in horizontal members 40 by means of a dependingportion 56 upon which is journalled wheels 51 having a gear section 58engaging the toothed rack 53 supported on members 4I).

Movement of the die holding plate 45 towards and away from die holdingplate 35 is accomplished through the movement of pressure equalizingmember 41 caused by the oscillatory movement imparted to gear segments54. Motion is imparted to gear segments 54 through the reciprocatorymovement toothed rack 59 in engagement therewith, this reciprocatorymovement being accomplished by the action of a piston 60 connected tothe toothed rack 59 by means of a rod 6|, piston 60 being located withinthe pressure cylinder 62. Movement of piston 60 within the pressurecylinder 62 is obtained through the use of a suitable pressure,preferably uid pressure, the latter being controlled through suitableconnecting valves located Within the distributing chamber 63 whichserves to connect either side of piston 62 through conduits 64 and 65located at each of its extremities. Any uid pressure can be used, but inthe present instance we employ oil under pressure, the same beingsupplied to the distributing chamber 63 through a .conduit 66 from asuitable oil pressure pump 61 driven by an electric motor 68 both beingsupported upon a depending portion of sub-frame 55. Portion of the pump61 and particularly the inlet conduits are located in the oil supplychamber forming part of the lower most portion of sub-frame 55. The oilunder pressure produced by pump 61 is controlled through the actuationof the suitable valves located within distributing chamber 63 containingsuitable valves for establishing the connection of i'luid to either sideof the cylinder 62, through conduits 64 and 65, this control beingaccomplished through the use of a lever 18 which can be manually ormechanically operated, movement-of lever 18 is transmitted to thedistributing chamberv 63 by suitable links 12 and 13.

With the object of insuring the safety of the operator and preventingthat molten metal be displaced from -the pressure chamber 24 to the dieswhen the same are out of proper engagement, we provide interlockingmeans between the pressure actuating means for pistons 32 which servesfor forcing the molten metal into the dies, and the operating meanscontrolling the movable die holding plate 45, so that, the piston 32 cannot be moved from its normal upperk position unless the dies are infixed cooperating relation. This interlocking means embraces the use ofan upperly projecting member 15 xedly carried by toothed rack 59 whichcoacts with the control 18 of admission valve 84 which controls theinjection of iluid under pressure to cylinder 33 for the operation ofpiston 32, which as hereinbefore described imparts movement to plunger38 forcharging the molten metal into the dies.

Member 15, as particularly shown in Figures 2h and 3, is provided with anarrow slot 88 terminating into a circular opening 8|. Slot 88accommodates the side or parallel walls 82 of the rectangular sectionformed at one end of rod 83 adjacent to the portion to which is fixedthe manual control or operating handle 18. The rectangular section ofrod 83 is supported on a circular opening formed on upwardly projectingmember 93 carried by sub-frame 55 which serves also as guiding means formember 15. The other end of rod 83 is connected to valve 88, the latterbeing actuated by rod 83 through the movement of handle 18. Valve 84serves to connect at will either conduit 86 or 81 located at top andbottom of cylinder 33 to the source of fluid pressure (not shown)supplied through pipe 88. As particularly shown in Figure 3, due to theintimate coaction of slot 88 and the side walls 82 of rod 83, member 18cannot be moved unless the rectangular portion of rod 83 is locatedwithin the circular opening 8| present in member 15. It should be notedthat the circular opening 8| will only be in registration with rod 83when the piston 68 and rack 59 are at their uppermost position, whichtakes place when the dies proper are in cooperative engaging relation.Under such condition, member 18 can be moved to/either direction tocontrol valve 84 for the injection of fluid under pressure to actuatepiston 32. If, however, the dies are not in proper cooperative relation,or rack 59 is not at its uppermost position, such actuation cannot takeplace. 'Ihis safety feature is of material importance as the moltenmetal is never displaced from the melting pot 24 by member 38 unless thedies are in proper engaging relation, thus preventing the metal frombeing splashed, causing injuries to the operator. The proper engagementof the toothed rack 59 with segmental gear 54 is accomplished by theprovision of rollers 98 and 9| bearing against the rear face of thetoothed rack member 59, these rollers being journalled on the side wallsof subframe 55.

For the purposeof using dies of diierent types in order to producecastings of different sizes and contours, the principalinstrumentalities forming the machine of our invention are capable ofrelative motion, and the sub-frame 55 and the element carried therebyfor this purpose is capable of adjustment with respect to the dieholding plate 35, so that the movement imparted to toothed rack 59 bypiston 68 to oscillate the pressure nuts 96 coacting with the threadedportions 91 of` members 43. By the use of spacers 94 which number andposition can be changed with respect to the front or rear face ofsub-frame 55 the position of such sub-frame and elements carried therebycan be moved as a unit thus permitting that dies of different depth canbe carried by the die holding plate 35 and 45.

In order to facilitate the movement of subframe 55 we have provided alever 99 which coacts with wheels 51 journalled upon projecting portions58 of sub-frame 55. 'I'he wheels 51, as hereinbefore pointed out, havesegmental gear sections 58 which engage the toothed rack 53 carried bythe supporting members 48. Movement of the lever 99 will serve forchanging the relative position of sub-frame 55 with respect to dieholding plate 35. For the purpose of providing an accurate adjustmentand proper engagement of the die holding members carried by the dieholding plates 35 and 45, respectively, the

pressure equalizing member 41 consists of two sections, each providedwith threaded cooperating portions |88 and 18|, respectively. Adjacentto the threaded portionv I8I is a clamp |82, the latter serving to holdthese portions in proper adjusted position preventing relative motionthus the desired length of member 41 is retained.

As particularly illustrated on Figure 10 an adjustable connection ispresent between rack 59 and its actuating rod 6I, this connectionconsisting in forming on 59 a slot |85 adapted to snugly receive thethreaded end |86 of rod 8|, the slot |85 serving to connect openings IIOand I I I which accommodate respectively nuts I I4 and II5 coacting withthe threaded portion |86 of rod 6I in this manner relative adjustment isobtained between rod 6I and rack 59 for the purpose of accurately timingthe point of closure of the dies in the cycle of operation and thisconnection presents the further advantages that the rack 59 has therequired liberty of movement to adjust itself automatically in its guideeliminating the necessity of a front bearing for toothed rack 59.

A special advantage of our invention consists in that the temperature ofthe melting pot 28 and molten material container therein, as well asthat of the pressure discharge chamber 24, is maintained uniformthroughout the' cycle of operation of the machine. In order t6accomplish this result, as particularly shown in Figure 6 of thedrawings, a pyrometer |28 is immersed into the molten metal andv throughsuitable wiring the same is connected to a temperature selector |24, thetemperature selector being provided with a manual temperature settingdevice |26 for the connected to a suitable source of energy and in turnserves to energize a relay (not shown) for the purpose of opening orclosing the circuit of an electric motor |28 directly connected to thefuel supply valve |30. It can be seen that any change in temperaturewill, in the present instance, change the electromotive force generatedby pyrometer |20 and will in turn actuate motor |28 for the purpose ofregulating the iiow of fuel to pipe 2| terminating in the furnacechamber I5. We provide a by-pass |32 around valve |30 for the purpose ofpermitting manual regulation of the fuel delivered to chamber l5. Thewall of furnace chamber |5 is provided with an opening |36 for thepurpose of allowing the escape of burned gases, and aiding in propercombustion and circulation of the heat supplied.

In order to control the temperature of surface of contact of the diewith the molten metal, the machine is provided with suitable coolingmedium conveyed by means of suitable pipes |40, |4| and- |43 to manuallycontrolled outlets adapted to be connected by flexible conduits to thedie proper.

The proper number of eiective conduits and the amount of cooling mediumcan be regulated manually by valves |44, thus keeping the dies at alltimes at a predetermined substantially uniform low temperature. It canbe seen that by the type of support of the pressure chamber 24 withinthe melting pot 20, the change of the pressure chamber can be eiectedany time without troublesome and time requiring work, and that thepressure and the amount of metal forced to the dies can be changed bythe simple expedient of substituting the pressure chamber and thecooperating metal displacing member or plunger actuated by means ofpiston This can be accomplished by the use of removable coupling i133attached to the piston rod 3|, this type of arrangement permittingdifferent types of metal displacing members to be used.

it should be noted that the delivering means of pressure chamber 2li areso positioned with respect to the melting pot 2li that a portion of thepassage 2, as well as spout or nozzle 28, are located just above theedge of the melting pot and of the normal level ofthe molten metalcontained therein so that this portion partakes of the heat appliedthereto so that a very small amount of metal is solidified in spout 28,the return stroke of plunger Bil acts to withdraw any molten metal fromconduit 2'! to the level of the molten material on melting pot 2i), thusleaving conduit 2l clear, and that it should also be noted that opening26 or" member 24 used for admitting molten metal lto duct 25 for itsinjecting into the die proper is located below the normal level of themolten metal so that the metal injected into the die is at all timespure and free from dross and other impurities. We have provided means tocushion the return stroke of the piston 32 actuated by fluid pressurefor the purpose of controlling the rapidity of movement and at vthe sametime the drawing back the metal in conduit 2'? when the metal displacingmember 36 is raised by means of piston 32, this means being in the formof a valve M2 which permits the slow ejection of the air when the pistonis returned to its upper-most position.

In order to automatically eject castings when the same are formed in thedie members, subframe 55 supports rods |46 and |48 which are received inopenings |50 and |52 respectively on the movable die holding plate 45.These rods serve the purpose of engaging the die ejecting plate |54carrying a plurality of knockout pins |56. As particularly illustratedin Figure 7, when the die holding plate |45 is moved away from dieholdingplate 35, the rods |46 and |48 engage the die ejecting plate |54,causing relative motion between the die and the ejecting plate wherebythe knockout pins |56, engage the casting thereby aiding in the removalof the castings from the die member. The rods |46 and |48 are capable ofadjustment in sub-frame 55 by the use of threaded portions |60 and |62coacting with nuts |64 and |65.

The operation of the machine as hereinbefore described, could besummarized as follows. One complete cycle of the operation is nowdescribed. Assuming that the machine is in the position shown in Figuresl and 6, wherein the sectional dies are in proper engagement the manualoperating lever 'i8 which serves to actuate the admission valve 84 movedfrom the full line position to the dotted line position in the directionof the arrows as shown in Figure 3, this movement will permit theinjection of iiud under pressure to the upper portion of cylinder 33whereby piston 32 will be moved downwardly, transmitting such motionthrough coupling |03 to member 30, the latter forcing the metalcontained in ducts 24 and 2l through nozzle 28 into the sectional dies,the actuation of member '18 can be accomplished in this instance due tothe fact that the rectangular portion of 83 is in registration with thecircular opening 8| of member 'i5 due to the fact that the sectionaldies are in proper engagement and toothed rack 59 is in its upper-mostposition.

The pressure exerted by the fluid medium in cylinder 33 forces at acomparatively high pressure per unit of area the molten metal throughthe displacement of member 30 in the die and holds the same until ithardens and the casting is formed. During this casting operation, thedie holding plate 35 has been rmly locked and detained in fixed positionwith respect to the nozzle or spout 28 of pressure chamber 24 throughbolts 36 as hereinbefore pointed out.

When the casting has hardened, the operating lever 'i6 is moved to itsfull line position whereby iiuid pressure is admitted' at the lower endof the cylinder 33 and at the same time the pressure at the upper end ofpiston 32 is released. As soon as the casting has been hardened and withmanual operating lever 'i8 in its normal original position, the movabledie holding plate 45 is moved to the position indicated in dotted linesin Figure i to cause the ejection of the casting. Movement of the dieholding plate 45 is accomplished through the manipulation of lever inthe direction indicated by the arrow whereby movement is transmitted tothe distributor chamber 63 through links 12 and '|3 whereby the oilunder pressure is supplied through conduit 65 to the upper extremity ofpressure cylinder 62, causing the downward movement of piston 60carrying the toothed rack 59 this movement of the rack 59 is permitteddue to the fact that the rectangular portion of rod 83 is in properregistration with slot of member '|5. The downward movement of rack 59causes the rotation of segmental gear 54, rotating the latter in aclockwise direction whereby pressure equalizing member 41 moves dieholding plate 45 to the position indicated by dotted lines in Figure 1,separating the elements A and B of the sectional die, thus movement ofplate 45 causes that the ends of rods |46 and |48 engage castingejecting plate |54 thereby forcing the knockout pins |56 to eject thecasting from the dies.

In order to cause the engagement of the die elements A and B, for thepurpose of stating the cycle of operation the die holding plate 45 ismoved from the dotted line position to the full line position. Thismovement is accomplished through the manipulation of lever 'III in theopposite direction as the one indicated by the arrow, this movementcausing the interconnection of conduit 64 with the oil under pressureand forcing piston 6U to its uppermost position whereby the segmentalgear member 54 is moved in a counterclockwise direction as indicated bythe arrows in Figure '7, causing the movement of die holding plate 45towards the relatively stationary die holding plate 35,'whereby theengagement of the sectional die members A and B is established. Movementof toothed rack 59 permits the proper registration of the circularopening 8l of member 15 with the coacting portion of manipulating rod 83upon which is xedly secured the manipulating lever 18. The machine isnow ready for another operation. From the above description, it can beseen that the rate of the operation of the machine and the rapidity ofthe cycle is only dependentlon the rate of cooling of the medium in thedie proper and that the rapidity of the cooling can be effected by theuse of a suitable cooling medium.

The apparatus disclosed herein forms the subject matter ot ourco-pending application Serial No. 120,112, led January 11, 1937.

It is apparent that, within the scope of the invention modications anddiierent arrangements may be made other than is herein disclosed, and

the present disclosure is illustrative merely, theinventioncomprehending all variations thereof.

What we claim is:

1. The method of making castings from zincbase material which comprisesmaintaining the material to be injected into a die at substantially atemperature ranging from three per cent to ten per cent higher than thematerial melting point; injecting said material into the die at apressure per square inch of not less than one thousand three hundredpounds, and not greater than two thousand pounds; and providing the rateof radiation of the die to maintain a uniform temperature at the diearea in contact with the material not to exceed sixty per cent of thetemperature of the injected material, the temperatures being determinedaccording to Fahrenheit scale.

2. The method of making castings from zincbase material which comprisesmaintaining the material to be injected into a die at substantially atemperature ranging from slightly above the melting point to ten per?cent higher than the material melting point; injecting said materialinto the die at a pressure per square inch of not less than one thousandthree hundred pounds, and not greater than the order of two thousandpounds; and maintaining the rate of heat radiation of the die so as toprovide a substantially uniform temperature at the die surface incontact with the material not to exceed sixty per cent of thetemperature at which the material is injected, the temperatures beingdetermined according to Fahrenheit scale.

. JOHN A. SCHULTZ, JR.

JOHN A. ZAPF.

